1. Field of the Invention
The present invention relates to improvements in the field of computer input devices, and more specifically to improved trackball systems and methods for rotating a three-dimensional image on a computer display.
2. Description of Prior Art
Computers are used to generate three-dimensional images in a variety of contexts. Three-dimensional images are used, for example, in computer-aided design (CAD), medical imaging, and computer games. Current systems commonly provide a user with the ability to rotate a displayed three-dimensional image around one or more axes. However, the user interface in these systems is often cumbersome.
For example, in certain systems, a user rotates a displayed image by using a mouse to click on on-screen arrows or by pressing designated keys on a computer keyboard. The displayed image then rotates around axes generally indicated by the user input. Other systems allow a user to rotate a displayed image by manipulating a trackball. In these systems, the displayed image rotates generally in a manner related to the trackball input.
One problem with the above systems is that they are often non-intuitive. It can require time for a user to become proficient with these input systems. Even an experienced user may, at times, find it difficult to quickly and reliably obtain a desired rotation of a displayed image.